/**
* Backtracking Runner
*
* Similar to SequenceRunner but takes a backtracking approach to guarantee finding
* a correct path if one exists with the given input sequence.
*
* Note:
*
* The first solution encountered is returned, additional solutions may exist but no attempt will be made
* to find them.
*
* As we need to backtrack consider how you're context object changes during transitions, you may need
* a customised __clone().
*
* This isn't efficient :) If your FSM is large or very recursive then you're going to run out of memory quickly...
*
* @param State $initialState
* @param Stateful $context
*/
public function __construct(State $initialState, Stateful $context = null)
{
$this->context = $context ?: new Context();
$this->context->setCurrentState($initialState);
$this->graph = new GraphBuilder($initialState);
}
/**
* Apply Transition
*
* @param mixed $input
* @param Stateful $context
* @param Runner $runner
*
* @return mixed
*/
public function apply($input, Stateful $context, Runner $runner)
{
$context->setCurrentState($this->to);
if ($this->action !== null && is_callable($this->action)) {
return call_user_func($this->action, $input, $context, $runner, $this);
}
if ($input instanceof InputSequence) {
$input->pop();
}
return $this->action ?: $this->to;
}
